<template>
  <div>
    {{a1}}
    <button @click="aa">
      +
    </button>
  </div>
</template>

<script>
export default {
  name: "HelloWorld",
  mounted() {
   
  },
  props : ['a1'],
  methods:{
    aa(){
      this.$emit('click',2)
    }
  }
};
</script>

<style scoped></style>
